The present invention relates to a process and to an apparatus for the production of elongate hollow bodies, more particularly tubes, pipes, or inner linings for such hollow bodies, from a liquid material, such as reaction mixture or melt, wherein the peripheral surface of a support rotating about a horizontal or slightly inclined shaft is covered with a separating film and the material is applied to this separating film. The resulting hollow body is continuously drawn in the axial direction of the shaft while observing the solidification speed of the material.
A separating film has been used in the production of such hollow bodies, which is wound onto a mandrel in the direction of the circumference thereof. The liquid material is subsequently applied to this layer. After the hollow body has been drawn from the mandrel, the separating film is then removed. The disadvantage of this method is that the spirally-wound separating film forms ridges on the inside wall of the resultant hollow body. Depending on the winding angle of the separating film and the height of the resulting ridges, there is produced a relatively large resistance to flow and a twisting effect on the flow on the inside wall of the tube. The ridges wear down in time. Hollows, due to cavitation, are produced behind the ridges which also cause flow resistance. The pipe prematurely wears because of this.
An object of the present invention is to reduce the interior pipe resistance and wear by a suitable process, and to provide a suitable apparatus for the production of such hollow bodies.